/**
 *
 * @author Kshitij VERMA (github.com/kv19971)
 * LEVENSHTEIN DISTANCE dyamic programming implementation to show the difference between two strings (https://en.wikipedia.org/wiki/Levenshtein_distance)
 *
 *
 */

public class LevenshteinDistance{
	private static int minimum(int a, int b, int c){
		if(a < b && a < c){
			return a;
		}else if(b < a && b < c){
			return b;
		}else{
			return c;
		}
	}
	private static int calculate_distance(String a, String b){
		int len_a = a.length() + 1;
		int len_b = b.length() + 1;
		int [][] distance_mat = new int[len_a][len_b];
		for(int i = 0; i < len_a; i++){
			distance_mat[i][0] = i;
		}
		for(int j = 0; j < len_b; j++){
			distance_mat[0][j] = j;
		}
		for(int i = 0; i < len_a; i++){
			for(int j = 0; i < len_b; j++){
				int cost;
				if (a.charAt(i) == b.charAt(j)){
					cost = 0;
				}else{
					cost = 1;
				}
				distance_mat[i][j] = minimum(distance_mat[i-1][j], distance_mat[i-1][j-1], distance_mat[i][j-1]) + cost;

								
			}
	
		}
		return distance_mat[len_a-1][len_b-1];
		
	}
	public static void main(String [] args){
		String a = ""; // enter your string here 
		String b = ""; // enter your string here 
		
		System.out.print("Levenshtein distance between "+a + " and "+b+ " is: ");
		System.out.println(calculate_distance(a,b));


	}
}
